There are gearboxes having a start-up clutch, one or more power shift clutches, shift clutches for shifting the various ratios or speeds of the gearbox and an actuation unit for actuating these clutches. During operation of these clutches, the coefficient of friction of power shift clutches or of the other clutches mentioned above may change, even for a short period of time, during the operation of the gearbox, for example, as a function of the clutch temperature. There are also other mechanical reasons for the change of the coefficient of friction such as wear and tear or abrasion of the friction plates of the clutches. This gives rise to a rather unpredictable control behavior, since a clutch, due to the difference between the value of the coefficient of friction selected by the actuation unit and the actual value of the coefficient of friction under certain circumstances, does not transmit the desired torque.
Thus, a need exists for an efficient method of controlling a gearbox, control unit and software for the control of the gearbox and/or gearbox for mitigating the problems associated with the above described gearboxes.
An exemplary embodiment of the present invention is directed to a method of controlling a gearbox, which is associated with a start-up clutch, at least one power shift clutch, shift clutches for shifting the gearbox into various speeds and a control unit for controlling the actuation of at least one selected clutch of the start-up clutch, the at least one power shift clutch and the shift clutches, the method comprising the step of: adapting a first coefficient of friction of the at least one selected clutch during operation of the gearbox by means of the control unit.
Another exemplary embodiment of the present invention is directed to a method of controlling a shifting process of a gearbox, which is associated with a start-up clutch, at least one power shift clutch, shift clutches for shifting various speeds of the gearbox and a control unit for controlling the actuation of at least one selected clutch of the start-up clutch, the at least one power shift clutch and the shift clutches, the method comprising the step of: controlling the torque which is adjustable by means of the selected clutch by means of the control unit, the controlling of the torque being performed by means of a torque control and a subsequent rotational speed control.